Power operated hammers



June 28, 1960 R. P. FITZGERALD POWER OPERATED HAMMERS s sheets-sheet 1 Filed Jan. 31, 1957 June 28, 1960 R. P. FITZGERALD POWER OPERATED HAMMERS 8 Sheets-.Sheet 2 Filed Jan. 3l, 1957 June 28, 1950 R. P. FITZGERALD 2,942,503

I POWER OPERATED HAMMERS Filed Jan. 3l, 1957 8 Sheets-Sheet 4 /as /o 80 fos/f Invenow.-

June 28, 1960 R. P. FITZGERALD 2,942,503

POWER OPERATED HAMMERS Filed Jan. 3l, 1957 8 Sheets-Sheet 5 .u TREADLE 18g Down ufweys 8 Sheets-Sheet 6 les Iawexaov R. P. FITZGERALD POWER OPERATED HAMMERS @57, ma #M June 28, 1960 Filed Jan. 31, 1957 m 0 7 8 u 8 a a e 3 a 4m@ .Mm f n M n. w n ...I l .,qrmfil, I t Illyltl l. H P.- o u wm l g 4 7 M \\wf m M June 28, 1960 R. P. FITZGERALD 2,942,503

POWER OPERATED HAWERS Filed Jan. 3l, 1957 8 Sheets-Sheet 7 June 28, 1960 R.P.HTZGERALD POWER OPERATED HAMMERS 8 Sheets-Sheet 8 Filed Jan. 31. 1957 faboveoutlinedthey are not nited States Patent Pneumatic Drop HammerCompa ABraintree Mass la corporationof Massachusetts ny l vFiled Jan. 31, 1957, Ser. No. '637,427 Claims. ;(Cl. .7B-25) :This'invention'relates to power` operated hammers and it 1s herein disclosed `as embodied vin a drop `rl'iamrner wherein annpperdie is carriedby aram which, under treadle control, -drops .ofV its own weight to bring the upper'die into operative 'engagement with a work piece supported on -a lower die. The .dies are readilyl removable "and replaceableeandthefformto which the work piece Vis shaped depends upon the selectionbf appropriate dies. -The ram, upon release of the treadle, is returned torits upper position -by l'fluid pressure.

Although :the various `features ofthe invention are hereyin ydisclosed vas embodied inea drop "hammer of -the vtype limited to such use' but Vcan .be :applied to power 'hammersrgenerally "-It is an object of the'invention top-rovi'de a power hammer in which-the: ram lis -notonly cylindrical and long lwith respect toits width-but-also is -Inassivewith respect "to 'ther cylinder -Withinvwhich i it moves and' has '.improved" means'forng-uiding vthe ramso as tofgivetmaximum support to the ram at the instant'ofimpaet. thereby to prevent deflection of vthe ram andthe att-acheddie andimprove the accuracy of the forged article. The invention Aalso includes improved adjustments and'improved -means for .cushioning the shock after impact lupon the -Work piece.

In accordancewith this object, a 'featurerof 'the illusvtratecl :machine consists in theprovision of-a ramcarry- `ing .upper frame which includes a pair of'heightwiseextending strong, rigidly supportedn parallel guide rods slidably engaged-by a-strong rigid-cross -piece onthe -lower endio'f the massive ramto support theram-against -any yitendcncyto deflect -atthe instantfof heavy yimpact of the -upper die against -a work piece supported onthelower `die. :Other features reside fin means for :adjusting the .lower die angularly with respect to the upper.y die, andfin means for adjusting the entire upper ram supportingh frame tand upper 'die transversely withrespectto-thellower die,

and also in a plurality of uid `pressure shock absorbing devices for supporting a base which carries .the operating instrumentalities of the hammer.

These andother ,objects andV featuressof ythe invention :will become apparent'upon a reading ofthe following description `of an illustrative powerhammer, [with-reference to the accompanying drawings, and will be'pointed out inthe claims.

1`n the drawings:

Fig. 1 is a front elevation fof -an 'illustrativepower hammer embodying theV invention;

Fig. -2 is -afsideelevation viewedifrom-the right of the hammer shown in Fig. 1;

`Fig. 3. is a vertical sectiontakenon -the.line--3 fof Fig-2; Y

Fig. 4 ris a large scale vertical-.sectionltaken onztheline 4=4 ,of Figul;

,Fig.5 is a-horizontal section taken .Cm the -line5-.5 of Figs. l and 2;

Fig. ,6,isa horizontal section takenongtheG-jof Fig. l; Fig.'7 is .a vertical section taken on ,the` line 7-17 of `Fig...6 showing one of the shock` absorbing supportsbe-V 4"fore the pressureuid is turned on;

. Patented June 28,1969

Fig. j'lO is a view similar to an intermediate portion of Y Fig."'2 but to a'larger scale;

Fig. ll is aplan view.of the power hammer to a large scaleand .with a paxtbroken away. y,

Fig. 12 is a' horizontaLsection of the main valve system showing the positions of the valves before the pressure 'duid is turned on;

Fig. 1,3 ,is a view similar to Fig. l2 but showing the positions ofthe valves after'the pressure fluid has been 'turned on; v

Fig. `l4"is a;view similarto Fig. 13 `but showing .the 'positions of the valves after'the treadle has been A'depressed; and

Fig. l5 `is a view similar to Fig. 1 4 but showing thefposi- 2()4 tions of the'yalvesnfter :thetreadle *has-becn-'al-lowed to ense.

The work"engaging'instrumentalities of `the "illustrated hammer-consist of alower'diejlt) (Figs. l 4and 3j) and an 'upper-die'ZZ. A workpiece, not shown, is placed upon vthe lower die '20 and then, through operator controlled mechanism, vthe upper die-'is causedtodeliver Laheavy '-blow to the work; piece and A.thereby shape thel workpiece toa desired form Idetermined by the `dies fselected'. "The 4downward or operative `:strokefofftheupperl die yis pref- Verablyetected by gravit-y and the upward'or returnestrok bypneumaticgpressure.

The lowendielztlhas aedepending dovetailZZi (seealso TFig. 4'5) engaging@ "slotforme'd in .an anvil T26. 'I'hisfslot extends 5in =a direction to l provide 'for forward zand -reariwardadjustment 'of the lower-fdie. "The dovetail '.24 isr -heldffin adjusted position1-byiagib z8. TheanvilZtnuis supportedforrotary adjustment in a base 3i) see. alsoFig. '6). To this-endthe intermediateportion` of the anvil e is inf-theform of'a collar 32andtlie ylower portion of the 40 anvil is .in the 'tormof aste1n34- ,depending` from the collar. The collar 32 :and` the: stem134.-are. journaled for rotary `adjustmentin thefbaseiSt). An annular Ihorizontalfsurfacemathe-:underside ofthe collarSZ rests'uponafcorfrespondingesurface; on the base:l 30- to provide heightwise support foritheranvilsZtS.

-Rotaiy:adjustmenty 'of'. the anvil 26 fis. eiected'i-by 'arpa-1r .of-adjusting screws 36:;(Figs. 51, 3 rand 5),..oniozpposite sidesof the-vertical axis oftheV anvilfandthreadedgthrough the base-30. The'ends lofthe screwsv 36v engagefatsi formed by recesses in fthecdllar 32,. either screwbeing loosenedfandfthe otherftightened to obtain the desired adjustment.

.The base 30;`does;not rest directly upon the floor or other supporting surfaces but Aupon-*four shock, absorbers ;.eaehhaving apistontiil (Figs. 7 andl8) from which eir- ,tends fupwardly agpistonf-rod 42ihaving its upper endfin 1supportingengagement'-Withthe baseil. Eachpiston f40 is movablegup:andl .down in 1a `cylinder 44;(seefalso .-Fig. 6.) :having 1a; constantly open orifice` 46 tbelowgthe -ypistonfforthe :fadrnission of air Vunder pressure. 'The space between eachrpiston and its cylinderfwall-is lsealed iof thegpiston by;,-a clampinggdiscj and screw f5.2.' .The two rearecylinders 44have their oriticesA directly-zcon- ;.nected togairfsupply conduits ,-54 --and-1 they also :have oriices l56, similar to -thecorifices 246; @by which "theaair pressure is cornmunicatedithrough .f conduits ,53 v`to the by: ,a leather packingn cupvf48eheld aga-inst -tfhefunder fac-:eV

to providethe desired pressure which should be sufficient to overcome the weight of the base 30 and all parts of the power hammer supported thereby, and thus normally to maintain all the pistons in their uppermost positions as shown in Fig. 8. Rubber buifers 68 are provided to keep the pistons 40 from hitting the heads of the cylinders 44.

When the upper die 22 strikes a work piece on the lower die 20, the impact transmitted through the anvil 26 and the base 30 will cause the pistons `40 to compress the air in the cylinders and thus cushion the shock transmitted to the floor. A ball type check valve 70 between the stem of the T coupling 60 and the conduit 62 prevents a sudden escape of air from the cylinders 44 back..

into the conduit 62 when impact further compresses it.` .The position of the pistons in the cylinders whenthe hammer is idle and before the air pressure is turned on is shown in Fig. 7.

The upper die 22 has an upstanding dovetail 72 (Figs. l and 3) engaging a slot formed in the lower end of a massive cylindrical plunger or ram 74. 'I'he ram serves a dual purpose in that it also acts as a piston rod to carry the piston by which the ram is elevated under pneumatic pressure. The slot in the bottom of the ram v extends in a direction to provide for forward and rearward adjustment of the upper die. The dovetail 72 is held in adjusted position by a gib 76. The ram 74 is movable heightwise in a strong bearing 140 formed in la top cross member 78 of an upper frame which com prises also a bottom cross member 80 rigidly joined to the top cross member by a pair of uprights 82. The center portion of cross member 80 is broken away in Fig. 1 to show to anvil 26. See also Figs. 4 and 6.

The entire upper frame 78, 80 and 82, together with the cylindrical ram 74 and the upper die 22 (Figs. l, 3, 4 and 5), is adjustable transversely as a unit with respect to the base 30. To this end a tongue 84 (Figs. 2, 3 and 4) depending from the bottom cross member 80 is guided by a complemental transversely extending groove formed in the upper surface of the base 30. This Y tongue and groove arrangement permits transverse relative movement only and prevents any turning of the upper frame relatively to the base 30. A pair of coaxial oppositely directed and transversely extending adjustingA screws 86 (Figs. 3, 4 and 5) have their ends engaging shallow recesses in upright walls of the bottom cross member 80. These adjusting screws 86 are threaded through upright posts 88 having lower portions which extend down into sockets formed in the base 30, the posts being firmly anchored to the base by coaxial clamping screws 90 threaded in the posts.

These clamping screws 90 are held down by heads 91 countersunk into the base 30. Y

The desired transverse adjustment of the upper die 22 is `effected by loosening one of the screws 86 and tightening the other. Undesired turning of the adjusting screws 86is prevented by set screws 92 threaded down into the upper ends of the posts 88 and prevented from damaging the threads of the adjusting screws by bronze plugs 94. Clearance spaces 96 (Figs. 3 and 5), formed in the bottom cross member 80, enable the latter to avoid interference with the posts 88 upon transverse adjustment of the upper frame; and a clearance space 98 (Figs. 3 and 5), formed in the bottom cross member enables it to avoid linterference with the anvil 26 as the upper frame may be moved transversely of the base in making any necessary lateral adjustment to align the dies.

The transversely adjustable upper frame, 78, 80, 82,

is held down on the base by four compression springs- 100 (Figs. 1, 2, 4 and 5). Each of the springs 100 surend bearing against a washer 104 backed by a nut 106 threaded on the post. The lower end of each spring 100 bears against a washer 108:,vhich rests upon a horizontal surface of the bottom cross `member 80. The lower portion of each post 102 is rmly anchored in a short horizontally disposed rod 110 which is free to turn in a somewhat oversized hole 112 formed in the base 30. A at 114 formed on the rod 110 facilitates construction. The nuts 106 are tightened or loosened to effect a desired com'- pression of the springs 100. The posts 102, while holding the upper frame 78, 80, 82 shown on the base 30,- are free to rock transversely in the transverse slots 103, 105 (Figs. l, 4 and 5) to accommodate transverse movements of adjustment of the upper frame.

As has alreadybeen mentioned, the ram 74 is guided for up and down movement in a bearing 140 in the top cross member 78. In addition to this bearing, however, supplemental guides are provided in the form of a pair 0f upright rigid and sizable rods 116 (Figs. 1 and 3) iinmovably secured at their upper ends in the top cross member 78 and at their lower ends in the bottom cross member 80. At the lower end of the ram 74 are rigid and preferably integral transverse extensions 118 in which are formed bearings having bushings 120 of considerable vertical dimensions (Fig. 3) for sliding and ram supporting engagement with the guide rods 116. The two extensions 118 together with the end portion of the ram 74 constitute, in effect a strong rigid cross piece on the lower end of the ram. The guide rods 116, being very rigid and acting in conjunction with the two bearings 120 and the upper' bearing 140, serve to overcome any tendency of the ram 74 and the related die 22 to deect or otherram proper and two laterally spaced bearings for the lower end of the ram, the lower bearings being supported i ter impact.

by the vertical parallel guide rods. This three point sup port for the ram provides extraordinary rigidity in holding the ram against any deection under conditions of olf cen- Impact occurs when the extensions 118 are most remote from bearing 140, thus giving bearing spacing which provides the best possible result. The massive cylindrical ram, longer than its diameter, provides for concentration of the mass of ram directly above the point of impact.

The upward stroke of the ram 74 is eiected by pneumatic pressure acting upon a piston 122 (Figs. 3 and 9) seated upon a shoulder 124 formed 0n the upper portion of the ram by a reduction in diameter. A leather packing cup 126 is clamped against the upper face of the piston 122 by a two part clamping disc 128. A two part clamping collar 130, having its split at right angles to the split of the clamping disc 128, has its under face engaging the upper face of the clamping disc. The two halves of the clamping collar 130 are drawn together by screws 132. The engaging faces of the clamping disc 128 and the clamping collar 130 are complementally inclined t0 effect a downward thrust of the clamping disc when the screws of the clamping collar are tightened. An overhanging shoulder 134, resulting from an increase in diameter of the ram 74, engages the upper surface of the clamping collar 130 to hold the latter against upward movement when clamping pressure is applied. A packing ring 136 on the shoulder 124 prevents air leakage through the piston assembly.

The piston 122 operates within a main cylinder 138 secured at its lower portion in a socket formed in the top cross member 78. The space between the ram 74 and 'the bottom of said socket is closed by a bronze bearing bushing 140 surmo'unted by an annular U-shaped leather packing 142. An air duct 144 (Figs. 9 and l1) in the `top cross member 78 opens into the cylinder 138 just above lthe packing 142. Secured upon the upper end of fthe cylinder 138 is a cylinder head 146 having vent holes 148 through which 'the space within the cylinder above the piston 122 is alwaysropen to the atmosphere. A valve 'system ffo'r controlling the admission and exhaust of air to Vand from the cylinder 138 will later be described.

The piston 122, Vbecause of the inertia of the massive cylindrical ram 74 as the ram rises,must be cushioned Vto prevent its striking a hard blow against the cylinder head 146. vTo this end a bumper cylinder 150 (Fig. 9) extends up from the head 146 of the main cylinder 138 andrhas a head 152 secured upon its upper end. A bumper piston 154, having a depending stern 156, is movable up and down in the bumper cylinder 150, the stein being guided by a bronze bearing bushing 158 and a bronze packingpgland 160 between which are held fibre packing rings 162. The space between the piston 154 and the wall of the bumper cylinder G is sealed by a leather packing cup 146 held against the upper face of the piston 'by a clamping disc 166 and screw 168.

, An air pressure conduit 170 connected to a conduit 196 (shown in Figs. 6 and ll and later to be described) communicates, 'through a conduit 172, with the space below the bumper piston 154 and also, through a needle valve 174 and .conduit 176, with the space above the bumper piston. With the air pressure turned off and the ram 74 down, the pressures Vabove and below the bumper piston 154 will beequal and the bumper piston will rest up'o'n fthe gland 160, withl the'stem 1.56 extending dov/n into the main cylinder 138. When the air pressure 'his 'turned o n and the ram 74 rises, it will strike the depending stern 1,56 and compress the air above the bumperrpiston 154. The -needle valve 174 impedes the escape of air above the bumper piston 154 and thus causes the pressure above the bumper piston to build up and cushion the upward stroke ofthe piston rod 74. The extent of such cushioning is determined by the adjustment 4of thel vneedle valve 174. Upon descent of ram 74, piston 154 will resume its original down position because the pressure coming from conduit 170 is'the same on the top and bottom o-f piston 154 but due to the larger effective area of the top 'of the piston 154, the downward force will exceed the upward force and as stated piston 154 willrn'ove to down position. n

A valve system for controlling the admission and exhaust of air to and from the main cylinder 138 comprises a pair of `cylindrical valve casings 178 and 180` (Fig. l`l and Figs. l2 to 15 incl.) mounted on the top cross member 78 and having their axes vertical. The valve casing 178 has three ports numbered 182,A 184 and 186 respectively and it houses a rotary valve 188 having three intercommunicating openings 190, 192 and 194. The port 182"communicates with the duct 144 `(see also Fig. 9) Ileading to-and from the main cylinder 138; the port 184 `is an inlet port and itcommunicates with the conduit 196 see'v also Fig. 6) leading from thejreducing valve 64; and the port 186 communicates through a duct 198, with a port-200 in the valve casing 180. Another port 202 in the valve ycasii1g'181) communicates, through a4 duct 204, with the air pressure conduit 196; and a third port 286 in the valve casing 180 communicatesy with the atmosphere through a; duct 208 and thus serves as an exhaust port.

lHoused, within the valve casing 180 is a rotary valve `210 having three intercommunicating openings 212, 214 and The valve 21.40 is operated by a vtreadle 218 (Figs'l and A rod 226 is pivotally connected at its lever 224. The lever 224 is fulcrumed on" the base 30,

Vtransmit a push as lwell as a pull.

and is connected to the lower end fof a :wire 228-which constitutes the operative element Uffa Bowdencable Vhaving '-a sheath 238 surrounding the wire and enablingit to through the wire 228 'and 'thereby rock `the shaft 234 and the 'valve 210 counterclockwise through anangle of ninety degrees. .Likewise release of the treadle 218 enables `the spring 222 to turn Ythe valve 210 clockwise thnough an angle of Vninety degrees.

Th valve 188 is operated automatically by a 'pair `of Vupper and lower spiral'cams 236 and 238 respectively, secured on an upright shaft 240 (Figs...1, 2, l0 and 1,1') Vwhich has bearings inthe upper frame. lApin Y242 (Fig.

2) von one of the vram 'extensions 118 engages the upper cam 236 as the ram 74 rises and therebyturns thegshaft 240 counterclockwise through an angle of `sixty degrees. This same pin 242, as the ram 74 descends, engagesthe lower cam 238 and thereby turns the shaft 240 clockwise through an angle yof sixty degrees. The cam shaft 240; is geared to the valve 188 by sprocket wheels 244 (Fig. 1 1.) and 246 and a chain 248, thegear ratio being such that a sixty degree rotation'of the cam shaft causes aninetyfde gree rotation of the valve. An idler pulley A250 .is provided for adjusting the tension of the chain V248.

From the foregoing description it will bev seenthat there .has been provided a power hammerhaving vadjustable vfeatures which make it possible for the dies to :be setin correct alignment at a great saving of time. The dies 20 and '22 may iirst be adjusted forwardly 'or b'ackwardly in theusual manner by the release and reeecuring'ofgibs 28 and 76. 1f the dies `at this point are not yaligned laterally, the adjusting screwsr 86 may be brought intovuse to shift the "entire upper frame including the ramv 74 .-and

associated guide rods 116 either to the right or tothejleft as may be needed to align the dies in .this direction. Vf-lfit appears that the misalignment is caused by angular dis-l parity, this may be corrected through the" operation of the anvil adjusting screws 36.V Upon b'ringingthe dies'into correct angular relationship, if it is found that thereis l still any longitudinal or transverse misalignnrent; the final correction maybe madethrough'the useof'thetransverse adjusting screws 86 'or ythrough the release lof either upper `or lower gib 76'or 28" and the shifting of the appropriate dieftowardthe front or'the rear 'of the machine'. y The operation of the vvillustrated power hammer will rnow Abe described. Assuming'the hammerV to be idle and `the air pressure to be turned oif, the ram 74 willbe'fdo'wn,

' with the upper die 22 resting upon -the 'lower die 20: and with thevalvesl 188 and 210 occupying the positionsishown 1in Fig. ll2. When the airpressure is'turne'dfon, air will pass from the conduit 19'6 through the"valve188'and the duct 144 and raise the ram 74. As the ram rises itjwill cause the upper cam 236 toturnthevalvelSS to thepositionshown in Fig. 13 and, although when the`vlve1'88is in v'thisV position it block-s the inlet port l184, Anevertheless air can `pass` throughfthe duct 7204port202r vlvef210, portf204), duct 198, port'18'6, valve 188port '182,duct 144 and so into the cylinder 138 `and thereby maintain vthe ram 74 at the upper end of its stroke. Upon depression ofk the treadle 218, the valve-210 will `turncounterclockwise from the position shown in Figs. 12 and [13 to the position shown in Fig. 14 and thereby `block the'admission 'of air thnough the `port 202 while, at they same time, it will connect the duct 198 with the exhaust duct t'1108, permitting air to escape to the atmosphere from'thecylinlder 138. The heavy ram 74 `will'thereupon.drop'its The sheath 7230 "is v 7 upper die 22 will strike the work piece and thereby in cooperation with the lower die 20 form the work piece to a desired shape. A complete lowering of the treadle will permit air to escape rapidly from the cylinder and thus enable the ram 74 to deliver a heavy blow;

ram 74 completes its downward stroke, engages the lower spiral cam 238 and thereby causes the valve 188to turn clockwise through an angle of ninety degrees to the position shown in Fig. 15, which is the same as the position shown in Fig. 12.

It the operator continues to hold the treadle 218 down, the vali/e210 will remain in the position shown in Figs. 14 and l5 and air will enter the cylinder 138 through the valve 188 while at the sai'ne time the escape of air from the conduit 196 will be blocked by the valve 188 and the escape of air from the duct 204 will be blocked by the 'v'alv'e 210. The r'am 74 will thereupo'rris@4 and, as it completes the upper portion of its s troke, it will cause the valve 188 vto turn counterclockwise from' the position shown in Fig. l to the'4 position shown in Fig. 14. With both valves in the positions shown `in Fig. 14, air from the cylinder 138 will escape through the exhaust du'ct 208 and the ram 74 will descend and this cycle will be repeated as long as the treadle 218 is held down.

When, however, the operator releases the treadle 218, the valve 210 will turn clockwise through ninety degrees to the position shown in Figs. 12 and 13, blocking the escape of air from the conduit 196 and the duct 204. Now, if the ram 74 is down, the valve 188 will occupy the position shown in Fig. 12 and will admit air to the cylinder 138. The ram 74 will thus be raised and the valve 188 will turn to the position shown in Fig. 13 and the hammer will remain at rest in raised position until the next depression of the treadle 218. If, on the other hand, the ram 74 is up when the treadle is released, the valves 188 and 210 will remain in the positions shown in Fig. 13 until the treadle is depressed. Thus, by releasing the treadle 218 as the ram completes its rst downward stroke, the operator can prevent the ram 74 from delivering an other downward stroke until he again depresses the treadle; or, if he continues to hold the treadle down, he can cause the piston rod to make as many downward strokes as he pleases.

In connection with the operation of the hammer as has just been explained, the significance and function of the four air cylinders 44 that support the hammer should be explained in more detail.

In conventional hammers of the type known to the art, it has been customary in many instances to support the hammer on springs but the supporting strength of the springs is not subject to adjustment. On the other hand, the air pressure that may be fed to the supporting cylinders 44 of the present construction may be varied at will by changing the setting of valve 64 or in case it was found not desirable to vary the pressure in pipe 196 then an additional valve like valve 64 could be introduced in the line 62, thereby to provide for exact control of the pressure in the four air cylinders 44.

In the operation of a power hammer of the present type it is customary and desirable to vary the force of the blow provided by the hammer according to the type of work being produced. As the blow is varied the compression and reaction of the supporting elements will vary according to the force of the blow. When springs are used as the supporting elements it is necessary that the springs be strong enough to absorb the heaviest blows and under such circumstances the spring, after being corripressed in absorbing the blow will cause an upward movement of the entire hammer to an elevation above the normal position of rest. The machine will then descend again compressing the spring and continue to bounce up and i down in an oscillating manner until the-vibration hasl completely damped itself out. This is objectionable and i aCCOrdiHgIi/,in prior art devices Snubbers, 0f Q11@ tvp@ QI;

a partial depression results in a lighter blow. The pin 242, as the from the spirit and 8 i another have been introduced in an attempt to minimize the vertical vibration set up by the springs.

It' a lighter hammer blow is needed for the work in question there is no means of varying the compressibility of the springs and as a result the most that can be hoped for through the use of springs is an average result in the absorption of blows of different force.

On the other hand, through the use of air cushions of the type disclosed herein in which the air pressure therein may be varied it will be seen that when heavy blows are to be made with the hammer the air cylinders may be tilled with an air pressure greater than that needed to merely lift the machine to its normal working position. The heavy blow will be sucient to compress the air in the cylinders, thereby to absorb the blow and on the rebound the piston 40 will engage the rubber buffer 68 which quickly and effectively damps the vertical oscillation.

If the blows to be applied by the hammer are lighter, then the air pressure in the cylinders may be reduced until in the situation of the lightest blows by the hammer there will merely be enough air pressure in the cylinders to have moved the four pistons to the tops of their strokes. That is to say, the pressure in the cylinders 44 will just -be suflicient to hold the pistons 40 against buffers 68. The light blows are then effectively absorbed as the four pistons 40 move downwardly against the lower pressure air and again, the rebound and tendency to oscillate is absorbed by the buffers.

From the foregoing it will be understood that the utilization of air cylinders achieves results not obtainable through the use of springs, namely, the supporting force can be varied to a pressure best calculated to absorb the particular hammer blows and secondly, means for snubbing the rebound can simply and easily be introduced in the cylinders on the upper sides of the pistons.

Obviously, the air cushions of the present type may be used with any type of hammer whether of xed or variable blow. If of the fixed type, the pressure in the cylinders will be set at a fixed pressure which provides the greatest shock absorbing qualities. If the hammer is of the type in which the blow may be varied, of which the preseiit construction is one, then means will be provided for varying the pressure in the cylinders as the striking force e of the hammer for particular types of work is varied.

Through the use of the air cushion supports it is possible to use a lighter anvil than would be the case if the hammer were mounted directly on the tloor. While this is also true of hammers mounted on springs still in the latter case it does not permit of Vthe use of as light an anvil as in the case of the air cylinders because of the inability to vary the supporting spring force. n l

It is my intention to cover all changes and modifications i of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures scope of the invention.

I claim: p 1. In a power hammer, a base, an anvil carried by said base and rotatable only about a vertical axis, means associated with said base for adjustably rotating said anvil,

a ram operating in an air cylinder, a frame carrying said air cylinder, said frame comprising a pair of uprights n itegrally joined by top and bottom cross members, said frame mounted on said base,v said bottom cross member formed to define a vertical opening therethrough, the upper end ot said anvil positioned in said opening and spaced on opposite sides from the walls of Vsaid opening,

and means for shifting said frame transversely .of said base for adjusting said frame with respect to said anvil whereby said ram may be adjusted transversely with re :spect to said anvil and said anvil may be adjusted angularly with respect to said ram,

2. In a power hammer, the structure set forth in claim 1, said ram having transverse extensions on its lower end,

and two parallel guide rods attached to the top and botftom cross members and positioned between the said uphaving a downwardly facing annular surface for cooperative engagement with the said annular surface of the base, said anvil having a depending stem, said base having a bearing for the cylindrical surface of said stern in which bearing the anvil can be rotated about a vertical axis only, and a pair of adjusting screws threaded in said base and having ends engaging recessed portions of the anvil whereby the screws can turn the anvil in opposite directions respectively, thereby effecting rot-ary adjustment of the lower die with respect to the upper die.

4, yIn a power hammer, the structure set forth in claim 3, said means for Iguiding the upper die for heightwise movement comprising a rigid upper frame formed of a pair of uprights. rigidly joined by top and bottom cross members and including two spaced parallel guide rods between said uprights, a cylindrical ram mounted in a bearing in the upper cross member of said frame, said ram having oppositely disposed extensions on the lower end thereof in surrounding and sliding engagement with said guide rods.

5. In a power hammer, a base, an anvil carried by said base, an upper frame having spaced uprights connected by top and bottom cross members, a 'blow applying element comprising a massive cylindrical ram longer than its diameter carried by said upper frame in a bearing for vertical movement,` said ram constituting the major portion or" the weightV of said element, dies carried by said anvil and ram between which a work piece may be formed upon the descent of said ram, a transverse ex-V tension at the lower end of said rain, two guiding means integr-al with said upper frame and located between said uprights and on opposite sides of said ram for cooperation with said extension whereby said ram will be sup ported against deilection at three triangularly disposed bearings, a cylinder above said frame, said ram movable in said cylinder and having a diameter greater than onehalf the diameter of said cylinder, and a piston attached to the upper end of said ram and slidable in said cylinder whereby said ram may be raised and dropped by the application of dluid pressure, said anvil -being rotatable about a vertical axis for a limited angular movement, said iframe being adjustable transversely of said anvil, and said dies being adjustable with respect to said ramy and anvil in a direction at right angles to the direc-tion of said frame adjustment.

6. In a power hammer, an upper frame for supporting a ram and upper die, said frame comprising a pair of uprights integrally joined by top and bottom cross members, a vertical opening through said bottom cross member, an anvil adjustable about its vertical axis for supporting a lower die, a base for supporting said anvil and said upper frame, a pair of members extending up from the base and rigid therewith, and a pair of horizontally extending oppositely directed adjusting screws threaded through said upwardly extending members and having their ends engaging portions of the bottom cross member of said upper frame whereby the screws can move the upper frame in opposite directions respectively, thereby to adjust the said upper die transversely with respect to the said lower die, said ian-vil having an annular horizontal under surface resting on a cooperating annular surface of said base and having an upper extension positioned within the contines of the said vertical openingV through said bottom cross member but spaced on oppositesides therefrom.

7. Means for resiliently supporting a power hammer of the type having a base on which are mounted the operating instrumentalities of the hammer, said instrumentalities includ-ing a ram, said means comprisinga supporting and shock absorbing systemcomprising a plurality of upright piston rods supporting said ybase and all associated operating instrumentalities, a piston on each rod, a cylinder in which each piston can reciprocate, said cylinders being adapted to rest upon a door, a conduit for conducting a gas under pressure to each cylinder below each piston, and a check valve in said conduit for preventing a sudden back ilow of pressure gas upon impact resulting from descent of said ram, thereby enabling the pressure gas to cushion the impact and thus minimize the shock transmitted to the oor.

8. Means `for resiliently supporting a power hammer as set forth in claim 7 and a pressure regulating valve in said conduit whereby the pressure in each of the said cylinders maybe varied to provide optimum resilient support of said hammer according to the force of the blow currently being applied tothe work by Isaid ram.

9. In a power hammer, la base, an anvil supported by said base for receiving a blow from a falling hammer, an upper frame, a hammer mounted for reciprocation in said upper frame, means for actuating -said hammer including means yfor controlling the velocity of said hammer at the moment of impact with said anvil, vertically compressible supporting means for said base, said supporting means comprising air cylinders and pistons movable therein, means for supplying compressed air to said cylinders to move said pistons and thereby raise said base and means for varying the said air pressure in said cylinders thereby Ito produce optimum shock absorbing conditions as re-V quired with respect to hammer blows on said anvil of particular force.

10. In a power hammer as set forth in claim 9 each cylinder including therein a buffer element located to be engaged 'by said piston upon the upward rebound of said piston -following ythe .absorption of the -force of a hammer blow by further compression of the air in said cylinders.

References Cited in the le of this patent lUNITED STATES PATENTS 18,004 Wilson Aug. 11, 1857 90,456 Maker May 25, 1869 248,505 Richardson Oct. 18, 1881 380,808 Leavitt Apr. 10, 1888 442,898 Kennedy Dec. 16, 1890 632,265 Horton Sept. 5, 1899 823,480 McLeod June 12, 1906 851,677 Lamb et al. Apr. 30, 1907 945,786 Kossel Jan. 1l, 1910 1,194,653 Monstream Aug. 15, 1916 1,870,499` Ernst Aug. 9, 1932 2,220,036 Fitzgerald et al Oct. 29, 1940 2,220,037 Fitzgerald Oct. 29, 1940 2,241,787 Murray May 13, 1941 2,261,312 Terhune Nov. 4, 1941 2,311,940 Grob Feb. 23, 1943 2,386,155 Weyer Oct. 2, 1945 $2,612,868 IFitzgerald Oct. 7, 1952 FOREIGN PATENTS 126,189 Great Britain May 8, 1919 

